Pulmonary artery hypertension (PAH) in children or adults is a progressive and fatal disease with a 3 year survival of 58%. PAH is characterized by sustained elevations of pulmonary artery pressure. Associated pulmonary artery hypertension (APAH) is PAH, which is associated with an underlying pulmonary, cardiac, or systemic disease. Idiopathic pulmonary arterial hypertension (IPAH) is a form of PAH that is present in the absence of an identifiable cause or associated underlying disease. Although advances in therapy and survival with PAH have been made, the etiology is still largely unknown.
In terms of diagnostic or prognostic methods for PAH, clinical functional assessment, such as the 6-minute walk, a test that measures the distance that a patient can walk on a flat, hard surface in a period of 6 minutes, is not applicable to children. In addition, specific diagnostic or prognostic biomarkers are lacking.
Vasodilators are the mainstay of PAH therapy. 20-30% of patients, however, do not respond to vasodilators. Non-responders have a poor prognosis and eventually require lung transplantation. Because the pathobiology is unknown, vasodilator therapy has significant morbidity and cost (˜$50,000/year). Further, the diagnostic or prognostic methods to easily and accurately identify patients that are unresponsive to therapy are lacking.